diff --git a/include/bank.h b/include/bank.h
index f078c73..e87430c 100644
--- a/include/bank.h
+++ b/include/bank.h
@@ -14,14 +14,6 @@ using BankResponse = std::pair<drogon::HttpStatusCode, Json::Value>;
 
 class Bank
 {
-    struct xxHashStringGen
-    {
-        inline uint64_t operator()(const std::string &str) const
-        {
-            return XXH3_64bits(str.data(), str.size());
-        }
-    };
-
     phmap::parallel_flat_hash_map<
         std::string, User,
         xxHashStringGen,
diff --git a/include/user.h b/include/user.h
index e03bc24..60beeb6 100644
--- a/include/user.h
+++ b/include/user.h
@@ -1,7 +1,6 @@
 #pragma once
 #include <json/json.h> //to be removed later
-#include <string>
-#include <xxhash.h>
+#include "xxhash_str.h"
 #include "log.h"
 
 struct User
diff --git a/include/xxhash_str.h b/include/xxhash_str.h
new file mode 100644
index 0000000..ee28675
--- /dev/null
+++ b/include/xxhash_str.h
@@ -0,0 +1,8 @@
+#pragma once
+#include <string>
+#include <xxhash.h>
+
+struct xxHashStringGen
+{
+    uint64_t operator()(const std::string &str) const noexcept;
+};
diff --git a/src/bank.cpp b/src/bank.cpp
index 748f3e6..c1cb885 100644
--- a/src/bank.cpp
+++ b/src/bank.cpp
@@ -106,7 +106,7 @@ bool Bank::VerifyPassword(const std::string &name, const std::string &attempt) c
 {
     bool res = false;
     users.if_contains(name, [&res, &attempt](const User &u) {
-        res = (u.password == XXH3_64bits(attempt.data(), attempt.size()));
+        res = (u.password == xxHashStringGen{}(attempt));
     });
     return res;
 }
@@ -114,7 +114,7 @@ bool Bank::VerifyPassword(const std::string &name, const std::string &attempt) c
 void Bank::ChangePassword(const std::string &name, std::string &&new_pass) noexcept
 {
     users.modify_if(name, [&new_pass](User &u) {
-        u.password = XXH3_64bits(new_pass.data(), new_pass.size());
+        u.password = xxHashStringGen{}(new_pass);
     });
 #if CONSERVATIVE_DISK_SAVE
     save_flag.SetChangesOn();
diff --git a/src/user.cpp b/src/user.cpp
index d697687..0d0db1e 100644
--- a/src/user.cpp
+++ b/src/user.cpp
@@ -5,7 +5,7 @@
      * 
      * @param init_pass initial password
      */
-User::User(std::string &&init_pass) noexcept : password(XXH3_64bits(init_pass.data(), init_pass.size())) {}
+User::User(std::string &&init_pass) noexcept : password(xxHashStringGen{}(init_pass)) {}
 
 /**
      * @brief User Constructor for admins
@@ -13,7 +13,7 @@ User::User(std::string &&init_pass) noexcept : password(XXH3_64bits(init_pass.da
      * @param init_bal initial balance
      * @param init_pass initial password 
      */
-User::User(uint32_t init_bal, std::string &&init_pass) noexcept : balance(init_bal), password(XXH3_64bits(init_pass.data(), init_pass.size())) {}
+User::User(uint32_t init_bal, std::string &&init_pass) noexcept : balance(init_bal), password(xxHashStringGen{}(init_pass)) {}
 
 /**
      * @brief User Constructor for loading
diff --git a/src/xxhash_str.cpp b/src/xxhash_str.cpp
new file mode 100644
index 0000000..5122082
--- /dev/null
+++ b/src/xxhash_str.cpp
@@ -0,0 +1,6 @@
+#include "xxhash_str.h"
+
+uint64_t xxHashStringGen::operator()(const std::string &str) const noexcept
+{
+    return XXH3_64bits(str.data(), str.size());
+}